Home / Industry News
ASTM A350 LF2 Flange for Low Temperature

Our Supply Range

Grades: ASTM A350/ ASME SA350 Grade LF2, LF1, LF3, LF5, LF6, LF9, LF787, Class 1, 2, 3

Outer Diameters: 1/2'' to 24'' in ASME B16.5, up to 60'' in ASME B16.47

Wall Thickness Schedule: SCH 10, SCH 40, SCH 160 comply with ASME B16.9

Pressure Class: Class 150, 300, 600, 900, 1500, 2500

Manufacturing Standards: ASME B16.5, ASME B16.47 A, B


Standards Scope

ASTM A350 covers several grades of carbon and low-alloy steel forged or ring-rolled flanges, forged fittings and valves intended primarily for low-temperature service and requiring notch toughness testing. They are made to specified dimensions, or to dimensional standards, such as the ASME and API Specifications referenced in Section 2. Although this specification covers some piping components machined from rolled bar and seamless tubular materials, it does not cover raw material produced in these product forms.


Product furnished in ASTM A350/ ASME SA350 shall conform to the requirements of Specification A961/A961M, including any supplementary requirements that are indicated in the purchase order. Failure to comply with A961/A961M will be considered nonconformance with A350. And in case of conflict between ASTM A350 and A961/A961M, this specification shall prevail.


ASTM A350 Flange Datasheet

Chemical Composition


Mechanical Properties

Tension Tests Requirements—The material shall conform to requirements for tensile properties in below table.


Heat Analysis and Product Analysis

A Chemical Heat Analysis and Product Analysis in accordance with Specification A961/A961M shall be made and conform to the requirements as to chemical composition prescribed in this table. Leaded steels shall not be permitted. Product analysis


Impact Test Temperature under ASTM A350 Flanges

Test Specimens by 10mm x 10mm



Impact test values: Charpy V-Notch Energy Requirements for specimens 10mm by 10mm



Referenced Documents

ASTM Standards:

A788/A788M Specification for Steel Forgings, General Requirements

A961/A961M Specification for Common Requirements for Steel Flanges, Forged Fittings, Valves, and Parts for Piping Applications

ASME Standards:

B 16.5 Steel Pipe Flanges and Flanged Fittings

B 16.9 Factory-Made Wrought Steel Butt-Welding Fittings

B 16.10 Face-to-Face and End-to-End Dimensions of Ferrous Valves

B 16.11 Forged Steel Fittings, Socket-Welding and Threaded

B 16.30 Unfired Pressure Vessel Flange Dimensions

B 16.34 Valves-Flanged, Threaded, and Welding End

B 16.47 Large Diameter Steel Flanges

ASME Boiler and Pressure Vessel Code


AWS Standards:


A 5.1 Mild Steel Covered Arc-Welding Electrodes

A 5.5 Low-Alloy Steel Covered Arc-Welding Electrodes


API Standards:


600 Steel Gate Valves with Flanged or Butt-Welding Ends

602 Compact Design Carbon Steel Gate Valves for Refinery Use

605 Large Diameter Carbon Steel Flanges


Manufacture - Melting and Forging


Melting Process - The steel shall be produced by any of the following primary processes: open-hearth, basic oxygen, electric-furnace, or vacuum-induction melting (VIM). The primary melting may incorporate separate degassing or refining, and may be followed by secondary melting using electroslag remelting (ESR), or vacuum-arc remelting (VAR).


Discard - A sufficient discard shall be made to secure freedom from injurious piping and undue segregation.


Forging Process

Material for forgings shall consist of ingots, or forged, rolled, or strand cast blooms, billets, slabs, or bars.


Heat Treatment

After hot working and before reheating for heat treatment, the forging shall be allowed to cool substantially below the transformation range.


Forgings grades except Grade LF787, should be heat treated in normalized, or normalized and tempered, or quenched and tempered. By manufacturer's option, material that performed in quenched and tempered could be normalized prior to the austenitize/quenched operation.


No limitation on size is intended beyond the ability of the manufacturer to obtain the specified requirements. However, Class 3 of Grade LF787 is only available in the quenched-and-precipitation heat treated condition.


Hydro-static Test

Forgings manufactured under ASTM A350/ ASME SA350 shall be performed with a hydro-static test compatible with the rating of the finished item. Such tests shall be conducted by the manufacturer only when Supplementary Requirement S57 of Specification A961/A961M is specified.


Product Related